Not many people see isotope hydrologists on the front line of the fight against climate change. But they are -- studying how to trap greenhouse carbon gas and bury it deep below ground in salty aquifers. The work is one topic being reviewed at the IAEA, when world experts in isotope hydrology meet 21-25 May in Vienna at an international symposium.
Over 280 participants will attend the International Symposium on Advances in Isotope Hydrology and Its Role in Sustainable Water Resources Development. Studies on carbon trapping and other topics from over 60 countries will be presented.
Carbon trapping -- or sequestration in technical terms -- is an emerging research area to combat global warming. It refers to natural or artificial processes that remove carbon from the atmosphere, to reduce or slow rising emissions through interaction with natural "sinks", mainly oceans, deep parts of the Earth's crust, or plants. In some processes, the carbon dioxide is injected into an underground water source where it dissolves and remains in long-term storage. That's where isotope hydrologists come in.
"Once the carbon dioxide is trapped in the water you want to make sure it stays put," says Brent Newman, a scientist in the IAEA's Isotope Hydrology section. "That's where isotope hydrology comes in. You use isotopes like carbon and oxygen to monitor if the carbon dioxide is leaking or flowing from the aquifer, and to assure the integrity of the aquifer is maintained. For carbon sequestration you need a brine aquifer where the water is thousands of years old. Isotope hydrology can tell you the age of the water. If it's very old, then it's unlikely the water is flowing out of the aquifer rapidly enough to be a problem. In addition, many brine aquifers have the capacity to absorb lots of carbon dioxide."
A range of other issues -- from water pollution to protection -- are on the symposium agenda. Participants will hear how isotope hydrology is being used to help countries protect their drinking water. In the Abidjan area of Côte d'Ivoire over recent years, the main source of groundwater quickly became contaminated. Using nitrogen isotopes, hydrologists identified urban sewage as the main contributor contaminating the groundwater.
In an area of Uganda where people are reliant on springwater for their drinking supply, scientists used isotopes to track where the springs were recharged, Mr. K. M. Kulkarni, an Isotope Hydrologist at the IAEA said. "Originally it was thought the water came from large mountain lakes, but the isotopes showed it actually came from swamps in the mountains," he said. These swamps are now protected so that the springs can continue to be a sustainable source of water.
"The symposium is an opportunity to highlight new advances, major breakthroughs and discussions on isotope techniques that are being applied in the hydrological sciences across the world," the Head of IAEA Isotope Hydrology, Mr. Pradeep Aggarwal, said. "With its focus on issues of sustainable development and environmental protection, the symposium speaks to the many ways that science and technology are helping countries solve water-related problems," he said.
A newly developed laser isotope analyser -- that the IAEA helped to test and modify -- will be demonstrated during the five-day meeting. It is the size of a small table top, and one-fifth of the cost of the standard device. "It will give developing countries greater self-sufficiency to perform their own analysis of water samples," Mr. Aggarwal said.
Other topics on the Symposium's agenda include surface water/groundwater interactions, new analytical approaches, coastal zone hydrology, wetlands, a variety of contamination problems, groundwater dynamics, land-atmosphere interactions, ecohydrology and waste disposal.